In the past two years, it has become increasingly obvious that a new syndrome has appeared whose hallmalk is acquired immunodeficiency and whose morbid consequences include life-threatening, opportunistic infection and neoplasm. Epidemiology indicates that the immunodeficiency is the result of a transmissable agent, and our own patient population has yielded evidence that a wider group of people are at risk than was originally appreciated. The current grant application seeks to bring a multidisciplinary approach to bear on this multifaceted problem. We have a large and active clinical infectious disease group serving a large high risk population. Many members of this group have expertise in the fields of immunology, virology, and cell biology which should enable us to identify patients, process material for culture and molecular biologic assay and carry out all the necessary steps in characteizing the clinical syndrome, immunologic derangement and etiologic agent or agents. The breadth of our group situated as it is in the center of the current epidemic gives us a unique capability to establish the complex interrelationships of this new and challenging syndrome.